Indicating system



1931. A. c. F INNEY 1 I INDICATING SYSTEM Filed lay 21, 1926 l'nvenbor IAlfred C. Finneg His Attorney.

Patented Aug. 4, 1931 onsenm H mm c. rum,

:12AM. A commu es on W. t n;

c umca'rmc My invention relates to improvements in indicating systemsfor electric apparatus. and more particularly to indicating systemsfor aplurality of dynamo electric machlnes as which are arranged to beconnected to a common bus whereby one indication is given when more thanone of the machines are connected to the bus and another indication whennone of the machines is connected to My invention will be betterunderstood mm the following description taken in connection withthe-accompanyiugdrawmgs and its scope will he pointed out in theappended it claims; a

In the accompanying drawings Fig. 1 11clustrates dia 'ammatically anindicating system embo, ying my invention, and F g.

2 illustrates n bodiment of my invention. p

Where a plurality of dynamo electric machines such as alternating currnt gen rators 3, 4, ,5, 6 are arranged to be conne ed to a bus 7,,wbiehmay be a neutral bueg ounde a directly or through a resistance," Al is dto have no m re than oneoi th sirable 1 bus connerators connccit dto thecptr 'nnously because of 1 118 0SS1b11 ty culating currentses cia y theriple frenm quency harmonic. e generators may be connected I switchessuch as circuit breakersfito a supply bus 9, only o has; being shown forclearncss.

R ferring now in particular to F g. 1', the neutral points, not n, ofthe three phase generators,,3, 4, 5,6, are brought out through loads 10which are arra ged to be connected to the neutral bus] t rough suitableconnecting'means or sw tches such as circuit breakers 13, 14, 15 and,16. -These are provided with auxiliary switches shown as movablecontact bridging members 11 which are arra d to close contacts 12 and nopen contacts 1 are 0 on as shown and vice versa when the circmtbreakers are closed. In accordance with myinvention, I

generators is connected to neutral bus diagrammatically another em-' inparallel through s itablewhen the circuit breakers rok vide means forindicati g when none 0 the 1m. licrlal 80. new.

, (and also when more than one of the'generators are connected to theneutral bus 7. This means comprises an electroresponsive device such asa relay 18 havingcelectromagnetic means including a winding ne t d andarran ed to have its energiZation varied in accor ance with the numberof generators connected to the bus 7 whereby o p oduce an effect'dependenton the numb r' of enerators connected t the bus 7. 1"

This re ay, through its relatively movable cooperating contacts 20 and21,is arr ed to control the circuit of suitable indicating means such asa red lamp 22 which is connected to a suitable source such as a controlbus 23. The relay l8 as shownis of the differential type and comprisesin addition m, mew max. ssszemnmo census. miners-Io to the winding 19,res tra1ning meaussuch as an opposlng wind ng 24 which is uppos d by theeffect of the winding 19 and which is connected to he enerized from thecontrol bus 23 so that the e set on the winding ,19 of fluctuations inthe control bus voltage, due, for exampleto heavy loads mposed thereon bcircuit breaker closmg coils and the, 11 e, is neutralized by thecorrespondm efiect of the winding '24. The circuit of thls winding mayinclude a current limiting means such as a resistance 25.

In order to have its energization controlled by the circuit breakers 13,14, 15 and 16, t e relay winding 19 is arran edto be connected acrossthe control bus 3throughthe contacts 17 of the circuit breaker auxiliaryswitches and resistances 26. The resistances 25 and 26 will be soproportioned thatwhcn only one of the circuit breakers 13, 14, 15, 16 isclosed the force or effect of the windin 24 will predominate to hold themovah e nember of the relay 18 inone position, that is'with the contacts20 and '21 open as shown. When, however, more than one 7 of thegenerator neutral circuit breakers are closed the force or effect of therelay winding 19 will predominate, since the resistance of the circuitof this windin will be decreased by virtue of the fact that more thanone of the'resistances 26 arethen connected in parallel with each otherand in series with the winding. In this case the movable member of therelay 18 is moved to another position such that the relay contacts i5)and 20 are closed and the red lamp 22 is lighted. This warns theoperator that too many generators are connected to the bus 7 Then noneof the generators is connected to the bus 7 as shown in Fig. l, thecircuit of a suitable indicating means such as a green lamp 937 which isconnected across the control bus 23 through the circuit break- 0auxiliary switch contacts 12 in series will be completed. The operatorconsequently knows that, it for example, the proper functioning oi theprotective apparatus of the system is dependent on grounding the system,one of the neutral circuit breakers should be closed.

In the embodiment of my invention shown in F 2, the generator neutralleads are arranged to be connected to the neutral bus 7 through suitableconnecting means such as circuit breakers 13, 1%, 15, 1G anddisconnecting switches 28 on each side thereof and in series relationtherewith. The circuit breakers and the disconnecting switches areprovided with auxiliary switches shown as movable bridging members 11arranged to close contacts 17 when the circuit breakers anddisconnecting switches are closed, and to open the contacts 17 when thecircuit breakers and disconnecting switches are open.

Again in accordance with my invention, I provide means comprising thedifferential relay 18 for indicating whether more than one or none ofthe generators is connected to the neutral bus 7. The winding 2i of thisrelay may be connected across the ccntrol bus through a resistance 25.In order to have its energization controlled in accordance with thenumber of generators connected to the neutral bus, the opposing winding19 is connected in series-parallel with the resistances 26 throi'lgh theauxiliary switch contacts 17 of the respective generator circuitbreakers and associated disconnecting switches.

When only one of the generators such as generator 3 is coninicted to theneutral bus, as shown in Fig. 2, the windings 19 and 24- will beenergized substantially alike and the movable contact 21 will be held inthe intermediate position shown. In order to prevent closing of thecontacts by vibration and slight inequalities of energizatioii, suitable biasing means such as centering springs may be provided.

If none 01" the generators is connected to the neutral bus 7, thewinding 19 will be deenergized and consequently winding 24 willpredominate. The relay contacts 21 and 29 then close and effect theenergization of suitable indicating means such as a green lamp 27 and abell alarm 31 through an auxiliary relay 82 whose contacts when closedcomplete the circuits of these indi cating devices 27 and 31 which areconnected across the control bus 23.

lVhen more than one of the generators are connected to the neutral bus,the winding 1 will predominate, since it is then connected across thecontrol bus 23 through more than one of the resistors 26 in parallel. Inthis case, the relay contacts 20, 21 close and effect the energizationof suitable indicating means such as a red lamp 22 and a bell alarm 23through an auxiliary relay whose contacts, when closed, complete thecircuits of these indicating devices which are connected across thecontrol bus 23.

lVhile I have shown and described my invention in considerable detail, Ido not desire to be limited to the exact arrangements shown anddescribed, but seek to cover in the appended claims all thosemodifications that fall within the true spirit and scope of myinvention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is,

1. In combination, a plurality of alternating current dynamo electricmachines each having a neutral point, a bus, means for connecting theneutral points to said bus and indicating means including a movablemember, restraining means for moving said member to one position,electromagnetic means opposing said restraining means for moving saidmember to another position and means for controlling the energization ofsaid electromagnetic means to cause the movement of said member to saidother position only when the connecting means are in position to connectmore than one of said machines to said bus.

2. In combination, a plurality of alternating current dynamo electricmachines each having a neutral point, a bus, means for connecting theneutral points to said bus and indicating means including a movablemember, restraining means for moving said member to one position whenthe connecting means are in position to connect none of said machines tosaid bus, electromagnetic means opposing said restraining means formoving said member to another position and means for controlling theenergization of said electromagnetic means to cause the movement of saidmember to an intermediate position when the connecting means are inposition to connect only one of said machines to the bus and to saidother position only when the connecting means are in position to connectmore than one of said machines to the bus.

3. In combination, a plurality of alternating current dynamo electricmachines each having a neutral point, a bus, means for connecting theneutral points to said bus and indicating means including a movablemember. restraining means for movmg said member to one posltion when theconnecting means are in a position to 011- nect none of sand machines tosaid bus,

electromagnetic means opposin said restraining means for moving saidmember to anotherposition and means for controlling the energization ofsaid electromagnetic means to cause the movement of said memher to anintermediate position when the connecting means are in position toconnect only one of said machines to the bus and to said other positiononly when the con-

